a song. Eight sentences describe the vineyard, of which seven give the characteristics, and one (Isa_5:7) the result. This "song" sets forth the doom of the Vineyard: the Parable (Luk_20:9-16), the doom of the husbandmen.
hath = had.
a very fruitful = oil's son. Can it refer to David and his anointing? Compare 1Sa_2:10; 1Sa_16:13; Psa_132:7. Compare Isa_5:7 -, below.
hill = horn. Hebrew. keren, always "horn" (seventy-five times). Only "hill" here.